Control valve fob fuel pumps



y 1934- E. SCHAEREN 1,958,410 3 CONTROL VALVE FOR FUEL PUMPS Filed June 21, 1933 L I5 n 1 K\% m r 1 E l I 2 L g) 7/7 rem/0r.

M Max/WW Patented May 15, 1934 UNITED STATES PATENT OFFICE Application June 21, 1933, Serial No. 676,809 In Germany June 21, 1932 1 Claim.

The present invention relates to a hydraulic safety device which prevents the revolutions of internal combustion engines from attaining too high speeds. If a member of the fuel injection 5 device is sticking fast the whole regulating device no longer works properly. A decrease of the amount of fuel injected into the cylinders is no longer possible and therefore the engine reaches an inadmissibly high speed. In existing devices members are provided which are influenced by the increased pressure of flow in the suction line created by the increased number of revolutions, in such a way that the piping leading to the injection device is closed up. Such devices have however the disadvantage that on account of the small periodical differences of pressure in the pipings they are very sensitive and that they do not always work satisfactorily.

This disadvantage is overcome according to the present invention in that a check member is interposed between the pressure side of the feed pump and the suction piping of the injection device. This check member is under the influence of the difference of pressure between the pressure and suction sides of the feed pump and a spring working in a sense opposite to the said difierence of pressure. But the said check member is not depending upon the difference of pressure between the pressure side of the feed pump and the suction side of the fuel injection device. In this way the check member closes up the fuel from the fuel injection device as soon as the difference of pressure between the pressure and suction sides of the feed pump is higher than the spring pressure.

On the drawing a constructional example of the subject of the invention is shown.

(1 represents the valve body, b the valve proper, and c the pressure spring which can be adjusted by the screw d. e is a stop against which the valve 1) abuts under the influence of the spring 0. f is the feed pump, by way of example a gear pump, by means of which the fuel is fed through the pipings m and g to the injection device which is not shown on the drawing. 11. is the suction line and m the fuel tank. Between the pressure and suction sides of the feed pump a throttle valve Z is interposed for regulating the fuel quantity whilst the space containing the spring 0 is connected to the suction side of the feed pump.

The stop e is adjusted in such a way that the passage 71. of the valve 1) is large enough so that the pressure of flow has no influence to the valve b. The pressure of the spring only is made use of for opening the valve b. This valve is under the pressure of the spring 0 which is about two atmospheres. When the difference of pressure of the pressure and suction sides of the gear pump exceeds the value of the two atmospheres due to increased number of revolutions the valve 1) is closed i. e. the supply to the injection pump is suspended until the pressure to the valve b has decreased, in consequence of a decrease of the number of revolutions of the engine below said value. Then the valve b is opened again under the influence of the spring 0. This spring 0 has such a tension that the valve b is not influenced by the periodical fluctuations of pressure in the piping g which take place in consequence of the periodical operations of the injection pump. By this invention a forced working of the safety device is obtained which responds only to an increased pressure of the fed pump i.

What I claim is:

In a hydraulic safety device the combination of a valve body providing a valve seat and a fluid chamber at each side of said seat, a valve in the body coacting with said seat, a spring acting to 30 move the valve from its seat, a stop limiting said valve movement, a fuel pump, a suction line from said pump to a source of supply, a pressure line from said pump to one of the fluid chambers, the pressure in said chamber acting to seat the valve, 5 a discharge line leading from the other chamber,a connection between the pressure and suction lines containing a throttle valve, a third chamber in the valve body in communication with the free end of the valve, and a connection from said third chamber to the suction line.

ERNST SCHAEREN. 

